Lipopolysaccharide induced upregulation of beta-1,4-galactosyltransferase-I in Schwann cell

Heat Shock Cognate Protein 70 Enhanced Integrin β1 Mediated Invasion in Cancer Cells

Purpose

Glioblastoma is one of the most common malignant cancers worldwide. In our previous work, we have shown that heat shock cognate protein 70 (Hsc70) functions as a positive growth regulator in glioma. We investigated the role of Hsc70 in integrin β1 mediated invasion of glioma cells.

Methods

In order to investigate whether the down-regulation of Hsc70 would affect the expression of integrin β1 subunit, HeLa cells were transiently transfected with Hsc70-AS or pcDNA3.0 vectors and the down-regulation of Hsc70 was confirmed by Western blotting. Human brain glioma U87 cells were stably transfected with Hsc70-AS or pcDNA3.0 vectors to further elucidate the relationship between Hsc70 and integrin β1 in human glioma cells. Cellular localization of integrin β1 was detected using immunofluorescence confocal microscopy analysis.

Results

Here we reported that down-regulation of the expression of Hsc70 in U87 cells by transfection with antisense cDNA specifically increased the expression of cell surface integrin β1 without changing its mRNA. Meanwhile, the integrin β1 125-kD mature form increased while 105-kD precursor form decreased when Hsc70 was down-regulated. Mechanically, the U87 cells transfected with antisense cDNA of Hsc70 decreased the Golgi localization of integrin β1, strengthened its interaction with integrin α5 subunit, and enhanced the adhesion ability to fibronectin (FN) and the phosphorylation level of focal adhesion kinase (FAK).

Conclusion

Overall, these results suggested that the down-regulation of Hsc70 expression could promote the expression of cell surface integrin β1 and subsequently inhibit glioma invasion phenotype.

ZFX modulates the growth of human leukemic cells via B4GALT1

Zinc finger protein X-linked (ZFX) is a key regulator of both embryonic stem cells (ESCs) and hematopoietic stem cells (HSCs), which is required for both Notch intracellular domain (NotchIC)-induced acute T-cell leukemia and MLL-AF9-induced myeloid leukemia in mouse models. However, the role of ZFX and its underlying mechanism in human leukemic cells remain unclear yet, though accumulating data have demonstrated that ZFX is aberrantly expressed in various human tumors and plays an important role. Herein, we found that ZFX was aberrantly expressed in various human leukemic cell lines and primary cells from leukemia patients compared with control cells. The silence of ZFX led to the growth suppression through either the deregulated cell cycle or the induction of apoptosis in various cells including K562, Jurkat, Namalwa, and THP-1 cells. The gene expression analysis revealed that UDP-Gal:βGlcNAc β 1,4-galactosyltransferase, polypeptide 1 (B4GALT1) was significantly down-regulated upon ZFX silencing, which is implicated in the response of K562 cells to the treatment of imatinib mesylate (IM). In addition, lectin blot assay showed that the galactosylation of glycoproteins in K562 cells was suppressed upon ZFX silencing. Interestingly, overexpression of B4GALT1 restored the growth and conferred drug resistance to ZFX-silenced cells. Taken together, we have demonstrated that ZFX is aberrantly expressed in multiple human leukemic cells and it modulates the growth and drug response of leukemic cells partially via B4GALT1, which suggests that ZFX is a new regulator of leukemic cells and warrants intensive investigations on this 'stemness' regulator in these deadly diseases.

The functional interaction between CDK11p58 and β-1,4-galactosyltransferase I involved in astrocyte activation caused by lipopolysaccharide

Glial cells are mediating the main activation of the central nervous system (CNS), being astrocytes the mayor glial cells in the brain. Glial activation may result beneficial since it could promote tissue repair and pathogen elimination. However, excessive glial activation mechanism can also have do harm to the tissue. β-1,4-Galactosyltransferase I (β-1,4-GalT-I) is a key inflammatory mediator that participates in the initiation and maintenance of inflammatory reaction in some diseases. Moreover, CDK11(p58) has been reported to be associated with β-1,4-GalT-I. We have found that CDK11(p58) and β-1,4-GalT-I are induced in lipopolysaccharide (LPS)-challenged rat primary astrocytes in a affinis dose- and time-dependent manner. CDK11(p58) regulates the expression of β-1,4-GalT-I by interacting with it. After the knockdown of CDK11(p58) expression, the expression of β-1,4-GalT-I decreases, and astrocyte activation downregulates. Inversely, the expression of β-1,4-GalT-I increases, and astrocyte activation enhances due to the overexpression of CDK11(p58). Knockdown of β-1,4-GalT-I reduces the activation potentiation caused by the overexpression of CDK11(p58), illustrating the function of CDK11(p58) to promote astrocyte activation depends on β-1,4-GalT-I. The interaction between CDK11(p58) and β-1,4-GalT-I to upregulate astrocyte activation is related to activating p38 and JNK pathways. These findings indicated that the functional interaction between CDK11(p58) and β-1,4-GalT-I may play an important role during astrocyte activation after LPS administration.